This invention generally relates to polishing devices, more particularly to hand-operable or portable devices that are suitable for restoring the surface finish to substrates that have an extensive surface area. The portable polisher according to this invention includes a pair of polishing rolls that are securely mounted onto a respective pair of elongated arbors that rotate along their respective longitudinal axes in a counter-rotating manner by the operation of a drive assembly that rotates one of the arbor and buffer assemblies in a clockwise direction and the other arbor and buffer assembly in a counterclockwise direction.
In industries such as aircraft maintenance and sheet metal working, it is often necessary to improve the surface characteristics and to enhance the surface appearance of substrates such as metal sheets, particularly sheet aluminum. In this regard, the aircraft industry demands specialty aluminum sheeting for fabrication over aircraft framing to thereby construct the outer skin of aircraft. This specialty sheeting and the constructed aircraft skin should be free of blemishes and oxidation. While it is possible to paint or otherwise coat these types of surfaces, an unpainted, highly polished aluminum skin is more corrosion-resistant than a painted aluminum surface, which must also be periodically stripped and repainted, requiring toxic chemicals and expensive special facilities. Moreover, a polished aircraft skin enhances the economical operation of an aircraft because it is lighter in weight and exhibits less drag than a painted aluminum surface.
Because of these advantages, it is desirable to utilize polished aluminum sheeting to fabricate aircraft skin. However, this desirable approach does have certain disadvantages in that any blemishes thereon cannot be simply covered up, as would be the case for a painted surface. This requires high surface quality standards during the manufacture of such aluminum sheeting, as well as special care during subsequent handling thereof during shipment, storage, and skin construction. When this type of sheeting is made at the mill, it is subjected to a very high speed in-line polishing operation which imparts a highly polished surface to mill-sized webs of sheet aluminum. Such large in-line webs are very effective in imparting the needed finish to these specialty products. However, immediately after these specialty sheets are manufactured, they are susceptible to being scratched, discolored or otherwise blemished by handling and transport devices, by the environment, and by human handling, particularly during operations such as fabricating the sheeting into the aircraft skin.
Accordingly, there is a need for a means by which surface blemishes can be repaired or removed after such highly polished specialty sheets are prepared at the mill. Certain attempts have been made in this regard by providing portable polishing units which are intended to achieve spot polishing of these blemishes. Typically, such portable polishing units impart a rotary sweep to a relatively flat buffing disk which is usually spindle-mounted.
Such units have proven less than satisfactory when compared with the results attained by large in-line polishers used at a specialty mill. Units of this type do not achieve the uniform surface finish characteristic of a finish applied at the mill. They tend to leave an uneven finish within which buffing marks are visible. Additionally, these devices, although portable, can be difficult to control because of their tendency to "walk" along the surface. Furthermore, since these specialty sheetings are exceptionally thin and pure, portable polishing units, which typically do not provide the precision polishing of the in-line apparatus used at the mill, run the risk of actually removing the thin, pure aluminum surface that is characteristic of this sheeting. In addition, previously known portable polishing units often do not provide the buffer speed needed to attain mill-like characteristics, and when attempts have been made to increase such speed of rotation, the risk of burning the surface is substantially increased.
Therefore, there is a need for a portable polishing apparatus which is easily controlled by a single operator and that can impart a mill-like finish with minimal risk of damaging the surface of specialty sheeting such as highly polished aluminum.
Such is accomplished according to the present invention by providing a portable polishing apparatus having a pair of elongated rotatable buffing surfaces, each of which rotates along its longitudinal axis. Each such longitudinal axis is generally parallel to the surface being polished, and the pairs of buffers counter-rotate with respect to each other, one of the buffing surfaces rotating in the clockwise direction, another rotating in the counterclockwise direction.
Accordingly, an object of the present invention is to provide an improved portable polisher.
Another object of this invention is to provide an improved, lightweight polisher having a pair of elongated counter-rotating buffs which also may be counter-oscillating along their respective longitudinal axes, which are generally parallel to the surface being polished.
Another object of the present invention is to provide an improved portable polisher that minimizes surface scratching while operating at a surface-feet-per-minute rate and with an amount of power that is on the general order of that achieved by a mill-scale, in-line polisher in order to impart a mill-quality finish to an aluminum substrate.
Another object of the present invention is to provide an improved portable apparatus for surface repair or surface preparation of a variety of generally flat substrates.
Another object of this invention is to provide an improved portable device that restores the polished finish of aluminum aircraft skin after it has been dulled by normal use.
Another object of the present invention is to provide an improved portable device for repairing blemishes on polished aluminum sheeting that occurs during handling, transport, and fabrication.
Another object of this invention is a portable polisher that removes oxidation or other blemishes quickly and efficiently without substantial removal of thin, pure aluminum surfaces.
Another object of the present invention is to provide a means and method for automatically applying polishing compound during the operation of a polishing device having counter-rotating longitudinal buffers.
Another object of the present invention is to provide an improved portable polisher having a handle assembly that facilitates remote operation thereof.